Abstract

The loss of amorphous hydrogenated silicon nitride is measured at 30 mK and 5 GHz using a superconducting LC resonator down to energies where a single-photon is stored, and analyzed with an independent two-level system defect model. Each film was deposited with different concentrations of hydrogen impurities. We find that quantum-regime dielectric loss tangent in is strongly correlated with N–H impurities, including . By slightly reducing we are able to reduce by approximately a factor of 50, where the best films show .